1. Field of the Invention
The present invention relates to a friction couple in which a friction surface that preferably suppresses noise and vibration is stably formed and maintained.
2. Description of the Related Art
Friction couples for automobiles and machine tools, which include a friction member for a clutch and a brake with a sliding member, require various capabilities. Especially, for developing a more effective clutch or brake, search for the material that does not cause noise or vibration in operation has been conducted.
One of the reasons that cause noise and vibration is nonuniform abrasion on the sliding member of the friction couple. As one of the methods for suppressing such vibration, nonuniform abrasion is suppressed by reducing aggression of the friction member against the sliding member. For the less aggressive friction member, there could be for example a friction member from which an aggressive material is reduced or a friction member to which a soft material such as rubber is added. However, the friction member, from which an aggressive material is reduced, is faced with the problem that the friction coefficient lowers. Also, the friction member with rubber suppresses the aggression of the material that attacks the sliding member by the elastic force of the rubber, but the rubber material deteriorates altered when the temperature rises. Unfortunately, due to the alteration of the rubber material, the suppression of aggression against the sliding member cannot be maintained for an extended period of time, and at the same time that the friction coefficient is reduced by the decomposed matter.
Japanese Patent Application Publication No. 2007-71220 (JP-A-2007-71220) discloses the technique that suppresses the vibration during friction caused by the above reasons. The technique of JP-A-2007-71220 relates to a friction couple that includes: a friction member that includes a fiber base material, a friction-regulating agent, a bonding agent, and a copper oxide; and a sliding member whose entire body or at least surface of the body is made of iron material. The inventor of the disclosed application JP-A-2007-71220 considers that, with such a friction member and a sliding member provided in the friction member, when the friction member and the sliding member slidingly contact each other, copper oxide and iron are reacted to produce a protective film on the surface of the sliding member, and thus the aggression of the friction member against the sliding member is reduced and nonuniform abrasion of the sliding member is suppressed. Unfortunately, the friction member of the friction couple of JP-A-2007-71220, which is produced by adding copper oxide to the non-iron material, has difficulty in forming and maintaining a protective film on the metal surface of the sliding member depending on the operating condition, pressure, speed, and temperature during friction.